SELF-ALIGNED CONTACT ETCH USING DIFLUOROMETHANE AND TRIFLUOROMETHANE

摘要

An oxide etch process that is highly selective to nitride, thereby being beneficial for a self-aligned contact etch of silicon dioxide to an underlying thin layer of silicon nitride. The process uses difluoromethane (CH>22<) for its strong polymer forming and a greater amount of trifluoromethane (CHF>3<) for its strong etching, and with a high diluent fraction of argon (Ar). The etch process is performed at a low pressure of about 20 milliTorr in a high-density plasma etching chamber.